Air-cooled floating roof



y 21, 1929- v c. F; H. BOHNHARD'T: I 1,714,207

AIR COOLED FLOATING ROOF Filed Jan. 14, 1928 Cl-IAPLES EH. BOHNHAPDTINVENTOR ATTO EY Patented May 21, 1929.

UNITED STATES GHAFLES I. H. BOHNHARDT, LOS ANGELES, CALIFORNIA. I i

fii ssua AIR-COOLED FLOATING ROOF.

Application filed January 14, 1928. Serial No. 246,758.

. My present invention relates to the art of oil storage with especialreference to tank roofs which float on the surface of the oil.

The objects, of my invention are I To provide a floating roof withprotective means for preventing the heating of the floating deck fromthe rays of the sun.

To provide in a floating roof for the disposal of rain water. i

To provide a floating roof in whichthe floating deck seams are not incontact with -the fluid in the tank. 5

To provide a floating roof with means for preventing the oil in the tankfrom getting onto theroof should the tank be filled to overflowing. 1 i

I attain these objects by the tank roof illustrated in the accompanyingdrawing .in which Fig. lis a section through a tank showing my improvedroof in position at the top-of its travel. v

Fkig. 2 is a detail of a unit of the floating dec Fig. 3 is a typicalsection through one of these floating deck units on the line A-A.

Fig. 4 is a detail of a water trap indicated in the center of the roofin Fig. 1.

Referring to the drawing, numeral; 1 indi- 30 cates a tank wall and 2the tank bottom. A

. vapor sealing means is indicated at 3 for preventing the escape ofvapor between the roof and the tank wall. An preferred means ofaccomplishing this en may be used, the means illustrated being thesubject of my United States Patent No. 1,597 ,04c6 and forming nopart'of my present invention. Float-' ing on the surface of the oil isthe floating,

deck designated in general by numeral 4. This deck is composed of aplurality of units 5 (Figs. 2 and 3). Supported by posts from thefloating deckis the weather roof 6, made of suitable plates supported byany referred system of purlins and bracing. is roof completely coversthe floating deck, protecting it from the heat of the sun. Furthermore,the space between the floating deck and the weather roof being open afree circulation of air takes place therebetween', materially helping tokeep the temperature of the floating deck below the temperature of itssurroundings. Evaporation caused by the heat of the sun is thuspractically eliminated.

The weather roof pitches radially towardthe center so that rain waterruns to the cenbuoyancy being obtained PATENT OFFICE.

ter. and escapes through the trap'indicated at 7. Referring to Fig. 4this trap is composed of a pipe 8 welded to the weather roof. Pipe 8extends through and is welded to plate 9 and reaches to within an inchor two of the bottom of cup 10. This cup is materially larger than thepipe 8 and extends upwards to within an inch or so ofthe plate 9, towhich it is secured by angle clips, 11. A second cup 12 welded to plate9 entirely surrounds cup 10. The bottom end of cup 12 is closed by plate13 which carries-the pipe nipple 14. A hose 15 is connected to nipple 14and hangs down so as to lie on the floor of the tank. In this manner anywater falling on the weather roof is conducted down to the water layerala ways found in the bottom of oil storage tanks. The arrows in Fig. 4show the flow of this water through the trap. By the use of this trapthe tank is always sealed preventing ingress of air even though it isentirely emptied of fluid.

Floating roofs used heretofore were usually made wlth a practically flatfloating deck, y the use of a vertlcal peripheralwall. In thisconstruction the seams'between the many plates of the deck are incontact with liquid and must be fluid tight. The buckling and warpin ofthese plates makes this tightness di cult to preserve. In my presentinvention the seams between deck plates are notin contact with the oiland consequently do not have to be fluid tight. I accomplish this bymaking the plates as shown in Figs. 2 and 3. I first bend the edges ofthe plate as shown at 16 then burn the corner out and weld along theline indicated at-17. In this way I form a flat bottom basin, fluidtight in itself. The height of the side walls 18 is made greater thanthe submergence depth will be when the roof floats on the oil. Theseunits are bolted or otherwise secured together as indicated at 19 toform the fioatin deck, the joints be-.. tween units being ma e up with acanvas 100 and red lead gasket or other suitable packing. Obviously thejoints between units are above the fluid level. This construction hasanother advantage in that the side walls 18 serve as beams to stifienthe floatin deck 105 and eliminate the need of any additional bracing.

The shape and weight of the floating units must be determined from thedimensions of the tank on which they are to work. To one 110 skilled inthe art of tank fabrication the eco nornical proportioning of theseunits would offer no difficulty;

Should a tank fitted with my present invention be filled to overflowing,the oil would break through the vapor seal 3 and would, if not preventedflood the basins of the floating deck. To prevent this the sheets 20extend above the top wall of the tank so thatany overflow simply runsdown the outside of the tank. In this same regard the inlet to pipe 8must be higher than the top of the tank to prevent the flooding of theWeather roof with oil. v

The posts indicated at 21 support the roof when the tank is entirelyemptied of oil.

It is obvious that the above principles of construction can be used withvarious modifications and I do not limit myself to the specificconstruction illustrated except deck and extending higher than the topof said tank when said deck occupies an upper position; a weather roofcovering and positloned above said floating deck, said roof pitchingdownwardly towards its center; a

water trap located at the lowest point of said 'upper side of said roof,a second passage upward communicating with the downward end of saidfirst passage, a third passage downward communicating with the upper endof said second passage, the said passages forming a continuous passageand the change in passage direction between the said second and thirdpassages being higher than the free top surface of said oil.

In witness that I claim the foregoing I have hereunto subscribed my namethis 9th day of January, 1928.

CHARLES F. H. BOHNHARDT.

